<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .box {
            width: 100px;
            height: 100px;
            background-color: gold;
            margin: 100px auto 0;
            /* 参1 动画名字 参2 动画时间 参3 动画曲线 参4 延时时间 参5 执行次数 大于0的数或者是infinite 参6 反向执行*/
            /*alternate 反向执行 会占用动画次数*/
            animation: move 1s ease 2s infinite alternate;
        }

        @keyframes move {
            from {
                width: 100px;
                height: 100px;
            }


            to {
                width: 300px;
                height: 300px;
            }
        }
    </style>
</head>

<body>

    <div class="box">


    </div>


</body>

</html>